#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<string.h>
int main()
{
	char arr[10000];
	int count[26], i, j;
	scanf("%s", &arr);
	int len = strlen(arr);
	int Max = 0, Min = len;
	memset(count, 0, sizeof(int) * 26);
	for (i = 0; i < len; i++)
	{
		for (j = 0; j < 26; j++)
		{
			if (arr[i] == 'a' + j)
			{
				count[j]++;
				break;
			}
		}
	}
	for (j = 0; j < 26; j++)
	{
		if (Max < count[j] && count[j] != 0)
			Max = count[j];
		if (Min > count[j] && count[j] != 0)
			Min = count[j];
	}
	printf("%d", Max - Min);
	return 0;
}